Filtering on classes and particulars of a packet destination address at lower-protocol layers in a networked device

Abstract

In one embodiment, a lower protocol layer in a network device filters packets based on a class and a particular of a destination address prior to sending information from the received packet to a higher protocol layer. For example, certain constrained networks include network nodes that do not have the ability to maintain a multicast distribution entry for each multicast address used in the network. By only forwarding on a portion of a multicast address, packets are often delivered to nodes in addition to the actual multicast subscribers. By filtering these incorrectly delivered packets at a lower protocol layer (e.g., layer-2 or layer-3), processing cycles at higher protocol layers are avoided. Additionally in one embodiment, class and particulars are deterministically determined (e.g., using a same hashing function) such that services can be discovered and used by subscribing to a corresponding multicast group.

What is claimed is: 
     
       1. A method, comprising:
 a higher-layer protocol of a network device subscribing for both a class and a particular with a lower-layer protocol of the network device, to receive information from packets that have a destination address that includes both the class and the particular, with the destination address being a standard Layer 2 or Layer 3 multicast address, and with the particular being a subclass of the class; 
 receiving, by the network device from an external source, a specific packet containing a specific destination address of the specific packet, with the specific destination address being a standard Layer 2 or Layer 3 multicast address and consisting of the class, the particular, and one or more additional values; and 
 in response to the lower-layer protocol determining that the higher-layer protocol has subscribed for both the class and the particular and that the specific destination address includes both the class and the particular, forwarding information from the specific packet to the higher-layer protocol. 
 
     
     
       2. The method of  claim 1 , wherein said determining that the higher-layer protocol has subscribed to receive information includes performing an exact match on the class said registered against the class in the specific destination address, and performing a partial match on the particular said registered against the particular in the specific destination address. 
     
     
       3. The method of  claim 1 , wherein the network includes a constrained network; and wherein the specific packet is said received by the network device after having been transported over one or more nodes of the constrained network that forwarded the specific packet based on less than all of the bits in the destination address. 
     
     
       4. The method of  claim 1 , wherein the lower-layer protocol is a layer-2 or layer-3 protocol. 
     
     
       5. The method of  claim 4 , wherein the higher-layer protocol is an application layer protocol. 
     
     
       6. The method of  claim 1 , wherein one or both of the class and the particular in the destination address are protocol independent hashed values. 
     
     
       7. A network appliance, comprising:
 one or more processing elements configured to perform operations; 
 memory; and 
 one or more of interfaces configured to send and receive packets; 
 wherein said operations, include: 
 a higher-layer protocol of the network appliance subscribing for both a class and a particular with a lower-layer protocol of the network appliance, to receive information from packets that have a destination address that includes both the class and the particular, with the destination address being a standard Layer 2 or Layer 3 multicast address, and with the particular being a subclass of the class; 
 receiving, by the network appliance in a network, a specific packet containing a specific destination address of the specific packet, with the destination address being a standard Layer 2 or Layer 3 multicast address and consisting of the class, the particular, and one or more additional values; 
 in response to the lower-layer protocol determining that the higher-layer protocol has subscribed for both the class and the particular and that the specific destination address includes both the class and the particular, forwarding information from the specific packet to the higher-layer protocol. 
 
     
     
       8. The network appliance of  claim 7 , wherein said determining that the higher-layer protocol has subscribed to receive information includes performing an exact match on the class against the specified class. 
     
     
       9. The network appliance of  claim 7 , wherein said determining that the higher-layer protocol has subscribed to receive information includes performing an exact match on the class said registered against the class in the specific destination address, and performing a partial match on the particular said registered against the particular in the specific destination address.